Multifunctional multilayer optical film

ABSTRACT

Optical component for use in a touch sensor and method of fabrication of same are disclosed. Optical component includes a multilayer optical film at least some layers of which are fabricated on the same manufacturing line and using the same manufacturing method. Each layer of the multilayer optical film is designed primarily to provide a desired associated property.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/216,507, filed Aug. 9, 2002, now pending, the disclosure of which isincorporated by reference in its entirety herein.

FIELD OF THE INVENTION

This invention generally relates to touch sensing devices. The inventionis particularly applicable to such devices used in electronic displaysystems.

BACKGROUND

Touch screens allow a user to conveniently interface with an electronicdisplay system by reducing or eliminating the need for a keyboard. Forexample, a user can carry out a complicated sequence of instructions bysimply touching the screen at a location identified by a pre-programmedicon. The on-screen menu may be changed by re-programming the supportingsoftware according to the application.

Resistive and capacitive are two common touch sensing technologies. Bothtechnologies typically incorporate one or more transparent conductivefilms as part of an electronic circuit that detects the location of atouch.

The performance of a touch screen is described in terms of variouscharacteristics of the screen. One such characteristic is opticaltransmission. Image brightness and contrast increase as a touch screen'soptical transmission is improved. High optical transmission isparticularly desired in portable devices where the display is oftenpowered by a battery with limited lifetime. Optical transmission may beoptimized by improving optical clarity of different layers in the touchscreen, and by reducing reflection at various interfaces. Typically,anti-reflection coatings are used to reduce reflection losses.

Another characteristic of a touch screen is the amount of glare.Polished surfaces in a touch screen specularly reflect ambient lighttowards a viewer. Such specular reflection is generally referred to asglare and will reduce the viewability of the displayed information.Glare from a polished surface is typically reduced by making the surfaceoptically diffusive. Such diffuse surface is sometimes referred to as amatte or rough surface. Glare may also be reduced by coating thepolished surface with a film having a matte or rough surface. Suchcoating is sometimes referred to as an anti-glare coating.

Another characteristic of a touch screen is durability. Generally, touchscreens are susceptible to physical damage such as scratching. A usermay use a stylus, finger, pen, or any other convenient touch implementto apply a touch. The ability of a touch screen to resist scratchingaffects screen durability, and hence, screen lifetime. Typically, atouch screen's durability is improved by coating surfaces that aresusceptible to scratching with a scratch-resistant film. Such a film issometimes referred to as an abrasion resistant film.

Another characteristic of a touch screen is overall cost. Generally,manufacturing cost increases as the number of layers in a touch screenis increased. As one screen characteristic is improved, one or moreother characteristics often degrade. For example, in an attempt toreduce manufacturing cost, the number of layers in a touch screen may bereduced, hence, compromising other properties of the touch screen suchas durability, optical transmission, or contrast. As a result, certaintradeoffs are made in a touch screen in order to best meet theperformance criteria for a given application. Therefore, there remains aneed for touch screens with improved overall performance.

SUMMARY OF THE INVENTION

Generally, the present invention relates to touch sensors and touchsensing displays where it is desirable to have a set of desiredproperties with no or little trade off and where it is further desirableto reduce manufacturing cost.

In one aspect of the invention a method of manufacturing a touch sensorcomponent includes manufacturing a glass substrate followed by usingatmospheric pressure chemical vapor deposition to deposit at least fourfilms onto the glass substrate where the first film is designedprimarily to have a desired optical clarity and sheet resistance, thesecond film is designed primarily to isolate the first film from thesubstrate, the third film is designed primarily to resist abrasion, andthe fourth film is designed primarily to reduce glare.

In another aspect of the invention a method of manufacturing an opticalcomponent for use in a touch sensor includes using the same depositiontechnique to form a multilayer optical film onto a glass substrate allfabricated on the same manufacturing line where the multilayer opticalfilm includes a first film designed primarily to have a desired opticalclarity and sheet resistance, a second film is designed primarily toisolate the first film from the substrate, and a third film is designedprimarily to provide a desired resistance to abrasion.

In another aspect of the invention a method of manufacturing amultilayer optical film for use in a touch sensor includes forming aglass substrate on a manufacturing line, and on the same manufacturingline and using the same film deposition technique to deposit atransparent conductive film primarily designed to provide a desiredoptical transmission and sheet resistance, and a barrier film designedprimarily to isolate the conductive film from the substrate.

In another aspect of the invention an optical component for use in atouch sensor includes a substrate manufactured using a float technology,and at least three films formed onto the substrate using the sametechnology where at least a first film is designed primarily to providea desired optical clarity and conductivity, at least a second film isdesigned primarily to isolate the first film from the substrate, and atleast a third film is designed primarily to provide resistance toabrasion.

In another aspect of the invention a touch sensitive display includes afloat glass substrate and at least four films formed onto the glasssubstrate using an atmospheric pressure chemical vapor depositiontechnique where the first film is designed primarily for a predeterminedoptical clarity and electrical conductivity, the second film is designedprimarily for isolating the first film from the substrate, the thirdfilm is designed primarily for resisting abrasion, and the fourth filmis designed primarily to reduce glare.

BRIEF DESCRIPTION OF DRAWINGS

The invention may be more completely understood and appreciated inconsideration of the following detailed description of variousembodiments of the invention in connection with the accompanyingdrawings, in which:

FIG. 1 illustrates a schematic side view of an optical component inaccordance with an embodiment of the invention;

FIG. 2 illustrates a schematic three dimensional view of a touch sensorin accordance with another embodiment of the invention;

FIG. 3 illustrates a schematic side view of an optical component inaccordance with another embodiment of the invention;

FIG. 4 illustrates a schematic side view of an optical component inaccordance with yet another embodiment of the invention;

FIG. 5 illustrates a schematic three dimensional view of a touch sensorin accordance with another embodiment of the invention;

FIG. 6 illustrates a schematic side view of an optical component inaccordance with another embodiment of the invention;

FIG. 7 illustrates a schematic side view of a display system inaccordance with another embodiment of the invention; and

FIGS. 8A-8D illustrate schematic side views of four optical componentsin accordance with other embodiments of the invention.

DETAILED DESCRIPTION

The present invention is generally applicable to touch screens, touchscreens used with electronic display systems, and particularly where itis desirable for a touch screen to have high optical transmission, highcontrast, high durability, low glare, low reflection, and lowmanufacturing cost. The present invention allows the optimization of atouch screen's desirable properties with no or little trade off. Thepresent invention, furthermore, describes implementation of some of thelisted desirable properties into a single layer, thereby furtherreducing design and manufacturing costs.

A touch screen can work on the general principle that an otherwise openelectrical circuit is closed when a touch is applied. The properties ofa signal generated in the closed circuit allows detection of a touchlocation. Different technologies may be employed to detect a touchlocation. One such technology is resistive. In a resistive touch, anapplied touch brings two otherwise physically separated conductive filmsinto direct physical contact with one another. The physical contactcloses an otherwise open electronic circuit, thereby resulting ingeneration of a resistively coupled electrical signal. The properties ofthe generated signal allow detection of the touch location.

Capacitive is another technology commonly used to detect the location ofa touch. In this case, a signal is generated when a conductive touchapplicator, such as a user's finger, is brought sufficiently close to aconductive film to allow capacitive coupling between the two conductors.The two conductors are electrically connected to each other, forexample, through the earth ground. Properties of the generated signalallow detection of the touch location. Other viable technologies includesurface acoustic wave, infrared, and force.

The present invention is applicable to touch sensing screens where it isdesirable for a touch screen to be scratch resistant, have low glare,low reflection, high optical transmission, and low manufacturing cost.The present invention is particularly applicable to touch screensutilizing resistive or capacitive technologies to detect the location ofa touch. For example, one embodiment of the present invention is wellsuited for use in a capacitive touch screen where it is desirable tohave optimized abrasion resistance and anti-reflection properties withreduced manufacturing cost. Another embodiment of the present inventionis particularly suitable for use in a resistive touch screen where it isdesirable for the conductive sheets to have optically diffuse surfaceswith reduced manufacturing cost.

According to the present invention the overall performance of a touchsensor can be improved by designing each layer primarily to provide aparticular characteristic of the touch sensor at a desired level. Forexample, a given layer in the touch sensor can be designed primarily toprovide a pre-determined optical transmission and sheet resistance. Adifferent layer can be designed primarily to provide a pre-determinedminimum resistance to abrasion, and yet a different layer can bedesigned principally to reduce glare.

According to the present invention, where two or more desiredcharacteristics in a touch sensor can not at the same time beeffectively provided for by designing a single, multifunctional layer,each characteristic is provided for by designing a separate layerdedicated primarily to providing that characteristic at a pre-determinedlevel. For example, a conventional capacitive touch sensor typicallyincorporates an abrasion resistant film to protect a transparentconductive sheet from damage due to repeated touches. Typically the samefilm is also designed to reduce reflection. However, the optimum designvalues for the two characteristics of resistance to abrasion and reducedreflection typically require a compromise in one or bothcharacteristics. For example, effective abrasion resistant materialstend to have a higher index of refraction than materials used to reducereflection. In addition, a design to provide resistance to abrasiontypically requires a film thickness that can be substantially differentthan a design that effectively reduces reflection. As a result, it isdifficult for a single film to simultaneously provide sufficientresistance to abrasion and reduction in reflection. According to thepresent invention, a first layer can be designed primarily to providesufficient abrasion resistance and a second layer can be designedprimarily to reduce glare. The two layers can have different indices ofrefraction, thickness, and material composition.

According to the present invention, the potential increase inmanufacturing cost due to an increase in the number of layers can bemitigated by sequentially depositing at least some of the constituentlayers on the same manufacturing line. For example, the coatings can beapplied to a glass substrate during the glass manufacturing process. Forexample, the coatings can be applied to a hot float glass in orsubsequent to the float bath. U.S. Pat. Nos. 6,106,892 and 6,248,397disclose deposition of a silicon oxide coating on hot glass. U.S. Pat.No. 5,773,086 discloses deposition of an indium oxide coating to thesurface of a hot glass. In one particular embodiment of the presentinvention, a multilayer optical component is manufactured that includesthe following steps. First, a glass substrate is manufactured on a floatbath. Second, while on the bath or after removing the glass substratefrom the bath a barrier layer of silicon dioxide or tin oxide isdeposited onto the hot glass substrate using atmospheric pressurechemical vapor deposition (APCVD). Next, a layer of transparentconductor such as a fluorine doped tin oxide is deposited onto thebarrier layer. The transparent conductor is primarily designed to have apre-determined optical clarity and sheet resistance. The barrier layeris designed primarily to isolate the transparent conductor from thefloat glass. Finally, an anti-reflective film coating is deposited ontothe transparent conductor film using APCVD, where the anti-reflectivefilm coating is designed primarily to reduce reflection to a desiredlevel. It will be appreciated that additional layers can be deposited onthe same or a different manufacturing line using APCVD or a differentmanufacturing technique to provide additional functionalities.

FIG. 1 illustrates a schematic cross-section of a multilayer opticalfilm 100 in accordance with one particular embodiment of the presentinvention. Optical film 100 is a component suitable, for example, foruse in a touch sensor. Optical film 100 includes a substrate 101, atransparent conducting film 102, an abrasion resistant film 103, and ananti-reflection film 104. Substrate 101 may be flexible or rigid.Substrate 101 is preferably highly optically transmissive. Transparentconductive film 102 is designed primarily to provide a desired opticalclarity, sheet resistance, and sheet resistance uniformity. Abrasionresistant film 103 is designed primarily to provide optimum protectionagainst abrasion. Anti-reflective film 104 is designed primarily toreduce reflection to a desired level by using light interference. Thedifferent films in optical film 100 may each be a single layer ormultiple layers. For example, anti-reflective film 104 may include oneor more layers of high and low indices of refraction. Suitable materialsfor anti-reflective film 104 include materials having a low index ofrefraction, for example, in the range of 1.35 to 1.5, although in someapplications other indices of refraction can be used. In addition, theoptical thickness of each layer in the anti-reflective film film, wherethe optical thickness is defined as the product of the physicalthickness and index of refraction of the layer, is typically close to aquarter of a wave, for example, in the 50 to 150 nanometer range,although thinner or thicker films can also be used depending on theapplication. Materials particularly suitable for abrasion resistant film103 typically have a high index of refraction, for example, in the rangeof 1.6 to 2.7, although in some applications other indices of refractioncan be used. In addition, in order to provide adequate resistance toabrasion, the abrasion resistant film should be sufficiently thick, anda sufficient thickness may or may not be much larger than a quarterwave.

To reduce manufacturing cost, it is common in known constructions for asingle film to be designed to provide two or more properties. Asdiscussed above, however, this approach often requires conflictingdesign parameters which can result in reduced performance. For example,if in the optical film 100 of FIG. 1 a single film is designed toprovide the properties of resistance to abrasion and reduced reflection,the potential conflicting requirements of material composition, index ofrefraction, and thickness often result in a compromise in one or bothproperties. More specifically, for example, the thickness of abrasionresistant film 103, designed primarily to provide sufficient abrasion,may have to be larger than the thickness of anti-reflective film 104,designed primarily to reduce reflection to a desired level. In addition,the index of refraction of abrasion resistant film 103 is typicallylarger than that of the anti-reflective film 104. Therefore, if a singlefilm was designed to provide anti-abrasion and anti-reflectionproperties, a compromise would need to be made. The present inventionalleviates the need for this compromise by designing abrasion resistantfilm 103 primarily to provide a desired resistance to abrasion, andanti-reflective film 104 primarily to reduce reflection. Therefore, inthe present invention, each of these properties are independentlyprovided by separate films, each of which is designed primarily toprovide a specific property to the desired level without particularconcern for the compromise that is often required when attempting toprovide multiple functionalities in fewer layers.

While each of the films described in the present invention is primarilyresponsible for providing its associated properties in an overallconstruction, the films may contribute to properties for which they werenot primarily designed. For example, the abrasion resistant film maycontribute to reducing reflection even though the anti-reflective filmis designed to be the primary provider of anti-reflection functionality.

As another example, the thickness of transparent conductive film 102,designed primarily to provide optical clarity and conductivity, isgenerally different than the thickness of anti-reflective film 104designed primarily to reduce reflection. To reduce manufacturing cost,in known constructions a single film is typically designed to provideproperties of conductivity and reduced reflection. However, since eachproperty generally requires a different thickness, at least one of thetwo properties remains at an undesired level. The present inventionallows optimization of both properties by designing a separate film 102to provide a desired clarity and conductivity, and another film 104 tominimize reflection.

As discussed, manufacturing cost of optical film 100 can be reduced bycoating most or all the films in optical film 100 on the same suitablemanufacturing line. Exemplary manufacturing methods include chemicalvapor deposition (CVD), APCVD, vacuum deposition (such as evaporation orsputtering), solvent-based coating, cast and cure, and other similarcoating techniques.

APCVD is particularly advantageous when substrate 101 is made of glass.In this case, layers 102, 103, and 104 can be coated on the same generalline where the glass substrate is manufactured, thereby reducing cost.The layers can be sequentially deposited, for example at differentcoating stations, at elevated temperatures on a hot glass substrate.Deposition at elevated temperatures and on a hot substrate can beparticularly advantageous because such conditions tend to improveoptical, electrical, and durability properties of the deposited films.Durability includes mechanical, processing, and environmentaldurability. Alternatively, films 102 and 103 can be deposited usingAPCVD and layer 104 can be deposited using a different method such asvacuum deposition.

Vacuum deposition, such as sputtering, may be used to deposit layers102, 103, and 104. Substrate 101 may be flexible or rigid. For example,substrate 101 may be in the form of a roll of a polymeric material. Inthis case, layers 102, 103, and 104 may be coated sequentially on a webline.

Alternatively, the different layers of optical film 100 can be solventcoated or cast and cured. For example, the layers may be roll coated ona roll of flexible polymeric substrate. Such method is particularlyadvantageous where transparent conductive film is a transparent organicconductor. In this case, layers 102, 103, and 104 may be sequentiallycoated and dried/cured on substrate 101.

Optical film 100 is suitable for use in touch sensors and isparticularly suitable for use in a capacitive touch sensor. Optical film100 provides means by which high optical transmission, low reflection,high abrasion resistance, and optimum sheet resistance can be achievedwith no or little trade-off. It will be appreciated that while a givenlayer in optical film 100 is designed primarily to optimize a givenproperty, one or more secondary properties may also be optimized withoutcompromising the primary properties. Optimization of such secondaryproperties can be by design or incidental or consequential to theprimary objective. For example, in a given application where transparentconductive film 102 is designed primarily to provide clarity and opticalconductivity, the thickness of layer 102 can be such that the layer alsoreduces interfacial reflections. As another example, in an applicationwhere abrasion resistant film 103 is designed primarily to providesufficient abrasion, the film thickness can be such that the film alsoreduces reflection without compromising the primary intended property ofresistance to abrasion.

Optical film 100 may further include anti-glare properties by opticallydiffusing a reflected light. Four such exemplary embodiments accordingto different aspects of the present invention are shown in FIGS. 8A-8D.Optical film 800A in FIG. 8A includes a substrate 801A with asubstantially smooth surface 801A′, a transparent conductive film 802Awith a substantially smooth surface 802A′, an abrasion resistant film803A with a substantially smooth surface 803A′, an anti-reflective film804A with a substantially smooth surface 804A′, and an anti-glare film(anti-glare film) 805A with a diffuse surface 805A′. Layers 801A-804Aare similar to the layers in optical film 100 described in reference toFIG.

Anti-glare film 805A is designed primarily to reduce specular reflectionto a desired level for a particular application, for example, bydiffusing the reflected light. According to FIG. 8A, anti-glare film805A reduces glare by virtue of a matte surface 805A′. anti-glare film805A may further include bulk diffusion properties, for example, byincorporating particles having an index of refraction different thantheir surrounding material. Matte surface 805A′ may be generated in anumber of ways. For example, the surface may be generating by embossinglayer 805A against a matte tool. Alternatively, the matte surface may begenerated by appropriately choosing deposition parameters as film 805Ais deposited. For example, where anti-glare film 805A is solvent coated,drying conditions can be chosen to result in a matte surface 805A′ upondrying. Alternatively, anti-glare film 805A can be coated using vacuumdeposition, CVD, or APCVD in such a way that the resulting film has amatte surface. Alternatively, anti-glare film 805A can include a coatingof particles dispersed in a host material, where the particles impart amatte surface to the film by, for example, partially protruding throughthe host material. As yet another example, matte surface 805A′ may begenerated by casting and curing film 805A against a textured tool.Alternatively, anti-glare film 805A can be constructed by spraying amaterial such a sol gel, for example, in the form of droplets, onto film804A. The sprayed material can be the same as that of film 804A.

According to FIG. 8A, optical film 800A has anti-glare properties byvirtue of an additional film 805A. Alternatively, an anti-glare propertycan be achieved by roughening surface of anti-reflective film 104 ofFIG. 1. This is shown in FIG. 8B. Optical film 800B in FIG. 8B includesa substrate 801B with a substantially smooth surface 801B′, atransparent conductive film 802B with a substantially smooth surface802B′, an abrasion resistant film 803B with a substantially smoothsurface 803B′, and an anti-reflective film 804B with a matte surface804B′. Layers 801B-803B are analogous to the layers in optical film 100described in reference to FIG. 1. In this construction anti-reflectivefilm 804B which is designed primarily to reduce reflection has the addedanti-glare property because of surface 804B′. The anti-glare property isachieved with little or no compromise in the primary objective of film804B.

FIG. 8C illustrates another embodiment of the present invention. Opticalfilm 800C in FIG. 8C includes a substrate 801C with a substantiallysmooth surface 801C′, a transparent conductive film 802C with asubstantially smooth surface 802C′, an abrasion resistant film 803C witha matte surface 803B′, and an anti-reflective film 804C with a mattesurface 804C′. Layers 801C-802C are analogous to the layers in opticalfilm 100 described in reference to FIG. 1. In optical film 800C,abrasion resistant film 803C is designed primarily to provide sufficientabrasion resistance. abrasion resistant film 803C also has a mattesurface 803C′. When anti-reflective film film 804C is substantiallyconformally coated onto layer 803C, a matte surface 804C′ is createdwhich provides anti-glare properties for optical film 800C. Thisconstruction is particularly suitable, for example, where it is easieror more advantageous to generate a matte finish directly in layer 803Cthan in layer 804C. In optical film 800C, a matte surface is generateddirectly in layer 803C and indirectly in layer 804C by a substantiallyconformal coating of layer 804C onto layer 803C.

FIG. 8D shows an optical film 800D according to yet another aspect ofthe present invention. Optical film 800D includes a substrate 801D witha matte surface 801D′, a transparent conductive film 802D with a mattesurface 802D′, an abrasion resistant film 803D with a matte surface803D′, and an anti-reflective film 804D with a matte surface 804D′. Inoptical film 800D, first a matte surface 801D′ is generated directly insubstrate 801D. For example, matte surface 801D′ can be generated duringthe manufacturing of substrate 801D. Next, layers 802D-804D (similar tolayers 802C-804C) are sequentially and substantially conformally coatedresulting in a matte surface 804D′ in the anti-reflection layer 804D.For example, where substrate 801D is glass, surface 801D′ may begenerated using chemical etching. Alternatively, surface 801D′ can begenerated when the glass substrate is manufactured, for example, byforming the glass against a textured tool. Next, all the other layersmay be sequentially and conformally coated, at elevated temperatures, onthe hot glass substrate by, for example, using an APCVD method. Hence,using APCVD, optical film 800D can be manufactured with low cost andwith desired optical transmission, reflection, glare, abrasionresistance, and electrical conductivity.

It will be appreciated that the sequence or order of the differentlayers in FIG. 8 may be changed according to application. For example,in FIG. 8D, abrasion resistant film 803D may be deposited on substrate801D before depositing transparent conductive film 802D.

FIG. 2 schematically illustrates a capacitive touch sensor 200 inaccordance with an embodiment of the present invention. Capacitive touchsensor 200 includes a touch panel 210, electrical leads 205, 206, 207,208, and electronic circuitry 209. Touch panel 210 includes a substrate201, a transparent conductive film 202, an abrasion resistant film 203,and an anti-reflective film 204. The layers in touch panel 210 aresimilar to those described in reference to optical film 100 of FIG. 1.Touch panel 210 is a capacitive touch panel. Electrical leads 205, 206,207, and 208 electrically connect the four corners of transparentconductive film 202 to electronic circuitry 209. Electronic circuitry209 includes electronics and software for determining a location of atouch and processing the collected information as desired in a givenapplication. Electronic circuitry 209 further includes software forproviding an application dependant user menu and for processinginformation. As an example, when a user applies a finger touch to touchpanel 210 at location X, current flows through the four corners oftransparent conductive film 202. This current capacitively couples tothe user's finger or other conductive touch implement. Electroniccircuitry 209 then determines the location of the touch by comparing therelative magnitudes of currents flowing through the four leads connectedto the four corners of transparent conductive film 202.

Touch panel 210 can also include a pattern of resistors to linearize theelectrical field across the panel, which pattern is not shown in FIG. 2for simplicity and without any loss of generality. One suchlinearization method is described in U.S. Pat. No. 4,371,746.

Touch panel 210 can provide increased transmission, reduced reflection,and optimized abrasion resistance with no or little trade off. Substrate201 is preferably optically transmissive and is designed to providemechanical rigidity or flexibility as required in an application.Transparent conductive film 202 is designed to primarily provide opticalclarity and a desired sheet resistance. Abrasion resistant film 203 isdesigned to primarily make touch panel 210 resistant to abrasion. Suchabrasion may occur, for example, when a user touches the panel with ahard or rough stylus, or with repeated touches. Abrasion resistance isimportant to protect the transparent conducting film 202, and tomaintain optical, electrical, and cosmetic properties of touch panel 210during its expected lifetime. Anti-reflective film 204 is designed toprimarily reduce reflection, thereby reducing glare and increasingcontrast. Anti-reflective film 204 may be a single layer or amultilayer. Each layer in anti-reflective film 204 typically has apre-determined optical thickness, for example, close to a quarter of awavelength, for example, in the visible region. Each layer may furtherbe organic or inorganic. It will be appreciated that according to thepresent invention, properties of touch panel 210 such as opticaltransmission, sheet resistance, abrasion resistance, and reducedreflection can each be independently tuned to a desired level with no orlittle need for a trade off. It will further be appreciated that touchpanel 210 in FIG. 2 can be constructed analogously to the embodimentsdescribed in reference to FIGS. 8A-8D or any other suitable embodimentwith accordance to the present invention.

FIG. 3 illustrates a schematic cross-section of an optical film 300 inaccordance with another embodiment of the present invention. Opticalfilm 300 includes a substrate 301, a transparent conductive film 303designed primarily to provide optical clarity and electricalconductivity, an abrasion resistant film 304 designed to primarilyprovide anti-abrasion properties, an anti-reflective film 305 designedto primarily reduce reflection, and an anti-glare film 306 designedprimarily to reduce or eliminate glare. Optical film 300 furtherincludes a barrier film 302 designed to primarily isolate transparentconductive film 303 from substrate 301. Such isolation can be desired toreduce or eliminate potential undesired interactions between substrate301 and transparent conductive film 303. One such interaction may bechemical reaction between substrate 301 and transparent conductive film303 that may adversely affect, for example, optical and/or electricalproperties of transparent conductive film 303. As another example,substrate 301 may include particles or impurities which, in the absenceof barrier film 302, could migrate into transparent conductive film 303,thereby adversely affect electrical and/or optical properties oftransparent conductive film 303. Such migration may occur duringprocessing and manufacturing of optical film 300, during assembly,during use, or for other reasons. Barrier film 302 stops or reduces suchmigration. For example, substrate 301 may be glass having impuritiessuch as sodium, and transparent conductive film 303 may be a transparentconductive oxide (TCO). Examples of a TCO include indium tin oxide(ITO), fluorine doped tin oxide, antimony tin oxide (ATO), and zincoxide (ZnO), for example, doped with aluminum. In the absence of barrierfilm 302, impurities in the glass can migrate into the TCO, therebyincreasing its sheet resistance and/or reducing its optical clarity.Such migration may, for example, occur at elevated temperatures over ashort time, or at lower temperatures over a longer time period. Forexample, a TCO is typically deposited at elevated temperatures, forexample, 150° C. or more. At such temperatures impurities can migratefrom the substrate into the deposited TCO film, thereby reducing itsconductivity and/or optical clarity. Furthermore, electrical and opticalproperties of a TCO film can be improved if the film is baked at anelevated temperature subsequent to deposition of the film. The postdeposition bake is sometimes referred to as annealing. In the absence ofa barrier film, impurities may migrate from the substrate into a TCOfilm during annealing even if the TCO film was initially deposited atlow temperatures. In the absence of barrier film 302, it may bedesirable for substrate 301 to be substantially free of impurities.Impurity free substrates limit the choice of substrate and increase thecost. Adding barrier film 303 allows use of glass with impurities, suchas float glass.

Anti-glare film 306 is primarily designed to diffuse residualreflection, thereby further reducing or eliminating glare. Anti-glarefilm 306 may have anti-glare properties by virtue of having a roughsurface 307. Such rough surface may be generated while depositinganti-glare film 306, for example, by optimizing coating and dryingconditions. Surface 307 may also be generated using other methodsincluding embossing, microreplication, spraying, or other methods.Alternatively, anti-glare film 307 may include a bulk diffuser thatimparts a textured surface to the film. It will be appreciated that,alternatively, optical film 300 can have anti-glare properties byincorporating a construction similar to those described in reference toFIGS. 8A-8D.

It will further be appreciated that optical film 300 provides desiredoptical transmission, sheet conductivity, reflection, glare, andabrasion resistance with no or little trade off. Furthermore, opticalfilm 300 allows high temperature processing, for example, in vacuum orin close to atmospheric pressure environment, by virtue of isolatingtransparent conductive film 303 from substrate 301. In addition, one ormore of layers 304-306 can contribute to protecting the transparentconducting film 303 from undesired effects such as oxidation, impuritiesthat may exist in air, and other potentially undesired effects duringfurther processing. Optical film 300 is suitable for use in a touchsensor. For example, the optical film may be used in a capacitive touchsensor similar to the circuit shown in FIG. 2.

FIG. 4 describes a schematic cross-section of an optical film 400 inaccordance with another embodiment of the present invention. Opticalfilm 400 includes a substrate 410, a transparent conductive film 403designed primarily to provide optical clarity and electricalconductivity, and a barrier film 402 designed primarily to isolatesubstrate 401 from transparent conductive film 403. The different layersin optical film 400 are similar to those described in the embodimentdescribed in reference to FIG. 3. Transparent conductive film 403 has atextured surface 404 to reduce glare. Hence, in this particularembodiment of the present invention the transparent conductive film hasthe secondary anti-glare property without compromising the primaryproperties of optical clarity and sheet conductivity. Textured surface404 can be created during deposition of transparent conductive film 403.For example, in a vacuum deposition of transparent conductive film 403,the deposition parameters may be chosen to result in a final roughsurface 404. Alternatively, the surface can be roughened by apost-deposition dry or wet chemical or mechanical etch. Alternatively,(CVD) or (APCVD) can be used to deposit transparent conductive film 403with a finished rough surface 404. For example, barrier film 403 can bedeposited, using APCVD, on a hot glass substrate 401. Next, transparentconductive film 403 can be deposited, using APCVD, on a hot barrier film402 and substrate 401. It will be appreciated that each film in FIG. 4can include more than one layer.

As discussed previously, a particular advantage of APCVD is that most orall layers of optical film 400 can be deposited at atmospheric pressureand at elevated temperatures. Such processing conditions generallyreduce cost and improve optical and electrical performance. Furthermore,layers can be coated sequentially on the same manufacturing line tofurther reduce cost. Another particular advantage of APCVD is that thelayers can be coated on the same line the glass substrate 401 isproduced, thereby further reducing cost. Barrier film 402 reduces oreliminates migration of impurities from substrate 401 to transparentconductive film 403. Thus, inexpensive glass with impurities may be usedto produce the glass substrate. Barrier film 402, by blocking migrationof impurities from the substrate, allows deposition of transparentconductive film 403 at elevated temperatures without compromisingoptical and electrical properties of the conductor. It will beappreciated that, according to the present invention, optical film 400may have other layers such as an abrasion resistant film designedprimarily to increase resistance of optical film 400 to abrasion. Itwill further be appreciated that, similar to the discussion in referenceto FIG. 8, matte surface 404 may be generated directly in transparentconductive film 403, or indirectly, by for example, first generating amatte surface directly in barrier film 402, and then substantiallyconformally coating a transparent conducting film onto barrier film 402resulting in a matte surface 404.

FIG. 5 illustrates a schematic of a resistive touch sensor 500 inaccordance with another aspect of the present invention. Resistive touchpanel 500 includes a top sheet 530 and a bottom sheet 540. Top sheet 530includes a transparent conductor 511 that faces the bottom sheet.Electrodes 505 make electrical contact with transparent conductor 511.Bottom sheet 540 includes a substrate 501, a transparent conductive film503 designed primarily to provide optical clarity and sheetconductivity, and a barrier film 502 designed primarily to isolatesubstrate 501 from transparent conductive film 503. The top surface oftransparent conductive film 503 (surface 504) can be rough or textured.Electrodes 506 are in electrical contact with transparent conductivefilm 503. Leads 507 and 508 connect top transparent conductor 511 andbottom transparent conductor 503 to electronic circuitry 510.

An applied touch brings top and bottom transparent conductors, 511 and503, into physical contact with one another at the location of touch.Touch location is determined by first energizing electrodes 505 andusing conductor 503 to determine the y-coordinate of the touch location.Next, electrodes 506 are energized and top sheet conductor 511 is usedto determine the x-coordinate of the touch location.

Bottom sheet 540 provides a desired optical clarity and sheetconductivity. The roughened surface 504 reduces or eliminates glare. Inaddition, matte surface 504 reduces or eliminates optical interferencebetween top and bottom sheets, especially at or near a location of atouch. Such an optical interference is sometimes referred to as Newton'srings and is, generally, apparent to a viewer. Newton's rings aregenerally undesirable because they reduce contrast and interfere witheasy viewing of information displayed through touch sensor 500.Roughened surface 504 reduces Newton's rings to an acceptable level oreliminates them. It will be appreciated that, according to the presentinvention, touch sensor 500 provides desired optical clarity, glare,substantially invisible Newton's rings, desired sheet resistance, andreduced manufacturing cost with little or no trade off.

FIG. 6 illustrates a schematic cross-section of an optical film 600 inaccordance with another embodiment of the present invention. Opticalfilm 600 includes a substrate 601 with a rough top surface 604, abarrier film 602 with a rough top surface 605, and a transparentconductive film 603 with a rough top surface 606. Transparent conductivefilm 603 is designed primarily to provide optimum optical clarity andsheet conductivity. Transparent conductive film 603 also has a secondaryantiglare property by virtue of matte surface 606. Barrier film 602 isdesigned primarily to isolated transparent conductive film 603 fromsubstrate 601, and has a secondary antiglare property. Glare in opticalfilm 600 is reduced or eliminated by virtue of diffuse surfaces 604,605, and 606. Optical film 600 is suitable for use in a touch sensor andprovides desired optical clarity, glare, isolation of a transparentconducting film from a substrate, and reduced manufacturing cost withlittle or no trade off. Optical film 600 can be made by first creating adiffuse surface 604 in substrate 601. Next, barrier film 602 issubstantially conformally deposited onto substrate 601 so that topsurface 605 of barrier film 602 is also roughened or textured. Surfaces604 and 605 can be similar to one another in texture and level ofroughness.

Alternatively, diffuse properties of surfaces 604 and 605 may bedifferent. Transparent conductive film 603 is then substantiallyconformally deposited onto barrier film 602 so that top surface 606 oftransparent conductive film 603 is also roughened or textured. Surfaces604, 605, and 606 can be similar in texture and level of roughness.Alternatively, these surfaces can be different in texture and/or degreeof roughness.

Optical film 600 is particularly suitable, for example, where it isadvantageous to create a diffuse surface in the transparent conductingfilm by first generating a rough surface in a substrate and subsequentlycoating the substrate with a barrier layer and a transparent conductingfilm in such a manner that the roughness in the substrate, at least tosome degree, duplicates in the coated layers. For example, in someapplications it may be difficult or less advantageous to directly createa rough surface in the transparent conducting film 606. In such cases,such rough surface can be generated indirectly by creating a roughsurface in a substrate and replicating the rough surface by conformallycoating the other layers onto the substrate.

It will be appreciated from FIG. 6 that, alternatively, surface 604 ofsubstrate 601 may be substantially smooth. In this case, a rough surfacecan be created directly in barrier film 602, and replicated intotransparent conductive film 603 by substantially conformally coatingtransparent conductive film 603 onto barrier film 602.

Barrier film 602 reduces or eliminates undesired interaction betweensubstrate 601 and transparent conductive film 603. For example, barrierfilm 602 can reduce or eliminate migration of impurities. Alternatively,barrier film 602 can reduce or eliminate chemical reaction. In general,barrier film 602 isolates transparent conductive film 603 from substrate601. The isolation eliminates or reduces an undesired interaction thatwould, in the absence of the barrier film, affect the performance of thesubstrate and/or the transparent conducting film.

APCVD can be used to manufacture the multilayer optical film 600. Forexample, a glass substrate 601, such as a float glass, can bemanufactured using a conventional glass manufacturing process. Next, acoating of barrier film 602 is applied to the hot glass substrate. Thecoating temperature may exceed 400° C. The coating may be applied to theglass in a float bath or after it is removed from the bath. The barrierfilm conformally coats the glass such that a textured surface 605results in the barrier film. Next, a transparent conducting film 603 iscoated onto the barrier film. The conductive coating may also be appliedin the float bath and the coating temperature may exceed 500° C. APCVDis particularly advantageous for manufacturing optical film 600 becausesome or all layers can be manufactured on the same line and at elevatedtemperatures. Therefore, manufacturing cost is reduced. Furthermore,performance of the layers can be improved when deposited at elevatedtemperatures.

Alternatively, when advantageous, CVD or a combination of CVD and APCVDcan be used to manufacture optical film 600. For example, barrier film602 may be coated onto substrate 601 using APCVD and transparentconductive film 603 may be coated using CVD. The coatings can be done onthe same manufacturing line. Other suitable methods can also be used forcoating the layers. For example, transparent conductive film 603 can bea transparent organic conductor. In this case, the organic conductor canbe coated onto barrier film 602 using knife coating, screen printing,inkjet printing, or any other suitable coating method.

Substrate 601 may be rigid or flexible. The substrate may be polymericor any type of glass. For example, the substrate may be float glass, orit may be made of organic materials such as polycarbonate, acrylate, andthe like. Barrier film 602 may be silicon dioxide or tin oxide.Transparent conducting film may be a semiconductor, doped semiconductor,semi-metal, metal oxide, an organic conductor, a conductive polymer, andthe like. Exemplary inorganic materials include transparent conductiveoxides, for example (ITO), fluorine doped tin oxide, (ATO), and thelike. Exemplary organic materials include conductive organic metalliccompounds as well as conductive polymers such as polypyrrole,polyaniline, polyacetylene, and polythiophene, such as those disclosedin European Patent Publication EP-1-172-831-A2.

FIG. 7 illustrates a schematic cross-section of a display system 700 inaccordance with one aspect of the present invention. Display system 700includes a display 701 and a touch sensor 702. Touch sensor 702 includesan optical film according to an embodiment of the present invention. Forexample, touch sensor 702 can include optical film 100 of FIG. 1,optical film 300 of FIG. 3, optical film 600 of FIG. 6, optical films ofFIGS. 8A-8D, or any other optical film in accordance with the presentinvention. Display 701 can include permanent or replaceable graphics(for example, pictures, maps, icons, and the like) as well as electronicdisplays such as liquid crystal displays, cathode ray tubes, plasmadisplays, electroluminescent displays, organic electroluminescentdisplays, electrophoretic displays, and the like. It will be appreciatedthat although in FIG. 7 display 701 and touch sensor 702 are shown astwo separate components, the two can be integrated into a single unit.

All patents, patent applications, and other publications cited above areincorporated by reference into this document as if reproduced in full.While specific examples of the invention are described in detail aboveto facilitate explanation of various aspects of the invention, it shouldbe understood that the intention is not to limit the invention to thespecifics of the examples. Rather, the intention is to cover allmodifications, embodiments, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

1. A method of manufacturing a touch sensor component, the methodcomprising the steps of: forming a glass substrate on a molten metalbath; depositing by atmospheric pressure chemical vapor deposition atleast four films onto the glass substrate including: a transparentconductive film configured for detecting a touch on the touch sensorcomponent; a barrier film configured to isolate the transparentconductive film from the glass substrate; a protective film configuredto resist abrasion; and an antireflective film.
 2. The method of claim1, wherein the protective film is deposited after the transparentconductive film.
 3. The method of claim 1, wherein the protective filmis deposited before the transparent conductive film.
 4. The method ofclaim 1, further comprising forming an antiglare coating over the fourfilms.
 5. The method of claim 4, wherein the antiglare coatingincorporates particles to form a matte surface.
 6. The method of claim1, further comprising the steps of providing electrical leads connectingthe transparent conductive film to electronic circuitry for determiningthe touch location.
 7. The method of claim 1, wherein at least one ofthe protective film and the barrier film protects the transparentconductive film from undesired effects during high temperatureprocessing.
 8. The method of claim 7, wherein the undesired effectsinclude oxidation of the transparent conductive film.
 9. The method ofclaim 7, wherein the undesired effects include impurities reaching thetransparent conductive film.
 10. The method of claim 1, wherein theantireflective film protects the transparent conductive film fromoxidation or impurities.
 11. The method of claim 1, wherein thetransparent conductive film comprises indium tin oxide, fluorine dopedtin oxide, or tin antimony oxide.
 12. The method of claim 1, wherein thebarrier film comprises silicon dioxide.
 13. The method of claim 1,wherein the barrier film comprises tin oxide.